The present disclosure relates, in general, to electronics, and more particularly, to circuits and method for providing power to electronic devices. Such circuits may include a DC-to-DC converter, such as a DC-to-DC Inductor-Inductor-Capacitor (LLC) resonant converter.
A DC-to-DC LLC resonant converter circuit may have a power limit to protect the circuit from being damaged by an excessive power demand, or too allow the circuit to change an operational mode in response to the power demand being high. However, in existing circuits, the power limit may be imposed based on a measurement that does not always reflect the actual amount of power being output.
For example, a DC-to-DC LLC resonant converter may detect an overpower situation (that is, may determine that the output power has exceeded the power limit) based only on an integration of a value of a primary-side current. However, the integrated primary-side current value may not accurately reflect the output power when a switching frequency of the DC-to-DC LLC resonant converter changes, since the power output may depend on both the primary-side current and the switching frequency. As a result, power protection based on only the integrated primary-side current value may from time to time be activated when the power limit has not been exceeded, or fail to be activated when the power limit has been exceeded.
Accordingly, it is desirable to provide power limit protection in a DC-to-DC LLC resonant converter according to a reliable estimate of the real output power.
Those skilled in the field of the present disclosure will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of the embodiments.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments. This avoids obscuring the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the disclosures herein. The details of well-known elements, structures, or processes that are necessary to practice the embodiments and that are well known to those of skill in the art may not be shown and should be assumed present unless otherwise indicated.